Beneficial antioxidant substances found in green tea are absorbed by eye tissues, suggesting that green tea consumption could protect the eye against oxidative stress that can contribute to the development of glaucoma, cataract and eye diseases. A new Hong Kong study is the first to show that green tea catechins are actually passed from thegastrointestinal tract into the tissues of the eye. Analysis of eye tissues from rats that were fed green tea extract showed that eye structures absorbed significant amounts of individual catechins. The retina absorbed the highest levels of gallocatechin, while the aqueous humor tended to absorb epigallocatechin. The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours. (Green tea catechins and their oxidative protection in the rat eye. J Agric Food Chem. 2010 Feb 10;58(3):1523-34).